The present invention relates to an inflating cage for wheels with pneumatic tires. Many tire inflations, e.g. after tire repairs, are still carried out without any screening of the wheel, and it is well known that fatal accidents may occur once in a while if a tire explodes during the inflation. However, it has already been suggested and to a certain extend used that the inflation is carried out in a security cage, which may be a frame construction having sides of a net material so that, in case of a tire explosion, no tire bits or mounting parts are thrown outwards towards persons near the cage.
However, the problem still exists that a tire explosion may cause considerable damage, also if it is not connected with any tire bits, rim parts, or other objects being ejected, since an explosive air escape from an entirely or almost entirely inflated, maybe over-inflated tire may be so forceful that it can hurl a person several meters away from the tire. The risk could of course be countered by using an inflating cage with wall panels of a reasonably strong plate material, but for one thing, by using metal plates, insight into the cage will be hindered, and for another thing the cage will become considerably costlier and heavier than when using wall panels of net material.
With the present invention it has been recognized that it is feasible to obtain a securing against discharge of strong air pressure waves from an exploding tire through a cage wall of net material, if this material is embodied so as to break the concerned air flow by causing a change or rather a double change of direction in the flow.
A net wall of a net material with usual round wires gives a practically unhindered passage of an air pressure wave, whereas, it has been found that a net wall of a so-called stretch metal net material provides a considerable resistance to an air passage. A stretch metal net is particular in that the net wires or strips include flat metal strip portions, which by the stretching of the net structure twist into a position in which their plane sides are oblique in relationship to the plane of the net wall, and these strip portions will hereby have a deflating and thus weakening effect on an air flow hitting such a net wall.
According to the invention, this recognition is made use of by not only relying on the air break effect which a single wall of stretch metal net can supply, as by a suitably open-meshed net this effect will not, after all, be sufficient for a really effective weakening of a strong air flow from an exploding tire, but according to the invention a strongly increased and, in practice, very significant weakening effect is obtained by using a double layer of a stretch metal met material, such that the the obliqueness of the mesh strip portions in the respective two layers is of mutually opposite direction with respect to the substantially parallel planes of the walls themselves.
By using such a double net wall where the two net walls may be placed rather closely to each other, it is obtained that an arriving pressure wave will be deflected first in one direction and immediately thereafter in the opposite direction, whereby a considerable weakening of the air flow is obtained.
The two net walls may be placed with a mutual distance of e.g. 1-15 cm, preferably appx. 4 cm.
In a preferred arrangement the two wall layers of the double wall are of identical shape and are placed mutually offset such that the junctions of the mesh strip portions are located next to the middle of the mesh openings in the other layer, and vice versa.
The double wall may be placed as a screen in any suitable manner between the tire inflation area and a adjacent workshop area, but preferably an inflating cage is provided with said double wall on one or more sides.
In the following, the invention is described in more detail with reference to the accompanying drawing.